function s1_hello(){
	echo "hello, world!"
}

function s2_tell_who_i_am(){
	whoami
}

function s3_which_distro_do_i_use(){
	if [ -f /etc/os-release ]; then
		source /etc/os-release
		echo "NAME=\"$NAME\""
	else
		echo "无法确定发行版"
	fi
}

function s4_view_my_cpu_arch(){
	uname -m
}

function s5_show_first_scsi_disk_size(){
	sectors=$(cat /sys/block/sda/size)
	size_gb=$((sectors * 512 / 1024 / 1024 /1024 ))
	echo "${size_gb}G"
}

function s6_show_main_memory_size_in_megabytes(){
	free -m | awk '/Mem:/ {print $2}'
}
